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  1. hevans1944

    Direction of Current in AC circuits.

    How language is formed and used doesn't NEED an excuse, the Hopelessly Pedantic being excused from this discourse. Still, it's nice to see @Ratch is still alive and kickin' butt as per usual. I, for one, will continue to say "the Sun is shining, the Mississippi River is flowing, and current is...
  2. hevans1944

    Need Help with simple 9V circuit design.

    @Harald Kapp, thanks for the link. Although most folks don't get into trouble operating outside the SOA (Safe Operating Area) when using power MOSFETs as simple on/off switches, biasing and operating (or transitioning through) the linear region is fraught with perils. This applies especially to...
  3. hevans1944

    Need Help with simple 9V circuit design.

    MOSFETs do have a linear region, but when used as current switches in an on/off application such a this thread describes, you don't want to stay in the linear region very long, especially if switching large currents that could cause overheating of the device. MOSFETs can be constructed to have...
  4. hevans1944

    Switching Power Supply

    What makes you think this is possible? Who is the manufacturer of the switching power supply, what is the model number, how much output voltage at what current level will a single power supply produce? How many do you need to operate in parallel? Is there a provision for synchronous switching of...
  5. hevans1944

    Need Help with simple 9V circuit design.

    BS! The transistor is a MOSFET, acting as an on/off switch in series with the motor and the 9V battery. It does not have a "base," it has a "gate" controlled by TTL (Transistor Transistor Logic) logic levels from the touch switch. If you want to control the speed of the output shaft (this IS a...
  6. hevans1944

    Direction of Current in AC circuits.

    This is NOT a true statement. The use of "ground" whether it be an "Earth ground" or a power-line "neutral ground" or a "reference ground" or any other kind of ground has absolutely no purpose in any circuit design other than as one of a pair of points between which electrical potential can be...
  7. hevans1944

    Watt Minutes Meter for Small Electronics

    Does this watt-minute meter have anything to do with your previous thread from two years ago, involving sixty-four silicone insulated heaters mounted on a slowly rotating (~3 revolutions per hour) wheel? I am curious about the purpose of the rotating heater wheel and how, with just two wires...
  8. hevans1944

    Advice for a electronics noob on a squarepusher style mask.

    Hows about posting a link that we are actually allowed to visit? Yours throws this "403" error.
  9. hevans1944

    Recommendation for a noob.

    The Arduino is by far the easiest approach to embedding a computer in a project. Get familiar with Arduino first before moving on to PIC microprocessors. I like PICs because their programming is very intimately integrated with the hardware on the PIC, said hardware including many built-in...
  10. hevans1944

    Controlling an Actuator

    Looks like a pretty beefy actuator, although 250mm / 5mm/sec = 50 sec for full stroke. That speed might limit your throughput unless feeding and/or changing stock takes more than about a minute. Not much choice there if you already have the actuator. I assume your clevis will have some sort of...
  11. hevans1944

    Controlling an Actuator

    It might be a good idea to get the mechanics worked out first, since whatever you decide to use for the actuator will be specific to the band saw you have. Maybe post some drawings, or even hand-sketches, of how you will attach a motor-driven actuator (there are LOTS of these to choose from!) to...
  12. hevans1944

    Is there a name for this type of motor ?

    I wish I had "inherited" Grandfather's motor after he died... I like collecting old "junque" like that... but the thought never occurred to me. I could barely lift it anyway, much less put it to use. I didn't have enough foresight, as a young kid, to try to find and write down the name plate...
  13. hevans1944

    3 Phase Motor - 3 Individual Circuit Breakers - Detect if 1 Breaker Tripped And Shut Down Motor

    Current transformers are not necessary, and they are expensive and bulky too. The Alegro Hall-effect current sensor is inexpensive, small, and responds to AC as well as DC. It is the natural choice for making a go/no-go decision on whether a circuit breaker has tripped. For this application, AC...
  14. hevans1944

    Which type of sensor works for pigeons within 20 feet without tripping when a skytrain drives by

    Here is a brief blurb describing the Acconeer (http://www.acconeer.com) modular radar that @Nanren888 suggested. Picosecond (one thousand times better than nanosecond!) time resolution. Millimeter accuracy at ranges up to seven meters (twenty-something feet for those living here in the States)...
  15. hevans1944

    Is there a name for this type of motor ?

    I hate to bump this old thread, but the speed control principle that @Externet described was exactly the same as was used on a motor that my grandfather (a retired, West Virginia, deep coal mine electrician) had in his garage in Tennessee in the 1950s. It worked exactly as you described, varying...
  16. hevans1944

    Which type of sensor works for pigeons within 20 feet without tripping when a skytrain drives by

    Gee, folks... this is an application that requires RADAR! Distance-to-target detection is a fundamental property of RAdio Detection And Ranging or RADAR. There are several techniques used to discriminate among targets at different distances, but the earliest and simplest one was to measure the...
  17. hevans1944

    3 Phase Motor - 3 Individual Circuit Breakers - Detect if 1 Breaker Tripped And Shut Down Motor

    Yep. That seems to be the gist of this entire thread. Why do something simple and safe, when with a lot of effort you can complicate the hell out of it? In addition to my "simple" video solution, several other "solutions" also come to mind, although probably none of them are practical...
  18. hevans1944

    3 Phase Motor - 3 Individual Circuit Breakers - Detect if 1 Breaker Tripped And Shut Down Motor

    Very little voltage will be presented to the motor when the circuit breaker is turned off. The motor winding resistances are much less than 51 kΩ. When the circuit breaker is open, because there is a 51 kΩ resistor (also in series with two back-to-back inversely connected diodes, one of the two...
  19. hevans1944

    3 Phase Motor - 3 Individual Circuit Breakers - Detect if 1 Breaker Tripped And Shut Down Motor

    @Mahonroy, it looks like you are good at appreciating our advice and then ignoring it. The suggestion was to place the opto-coupler LED in parallel with the circuit breaker, not between the phase and neutral. It is also necessary to place an inverse-connected diode in parallel with the...
  20. hevans1944

    Looking for a power supply recommendation

    Testing a quad-copter on the bench prior to actually flying it, eh? What a concept! I would suggest you remove the four propellers, thereby removing the wind load from the motors. Your existing bench power supply might then work without resetting the control board. Of course, then the motors...
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